use super::{DeserializationError, Expression, Rule};
use crate::sys::{self, libc};
use std::os::raw::c_char;

bitflags::bitflags! {
    pub struct States: u32 {
        const INVALID = 1;
        const ESTABLISHED = 2;
        const RELATED = 4;
        const NEW = 8;
        const UNTRACKED = 64;
    }
}

pub enum Conntrack {
    State,
    Mark { set: bool },
}

impl Conntrack {
    fn raw_key(&self) -> u32 {
        match *self {
            Conntrack::State => libc::NFT_CT_STATE as u32,
            Conntrack::Mark { .. } => libc::NFT_CT_MARK as u32,
        }
    }
}

impl Expression for Conntrack {
    fn get_raw_name() -> *const c_char {
        b"ct\0" as *const _ as *const c_char
    }

    fn from_expr(expr: *const sys::nftnl_expr) -> Result<Self, DeserializationError>
    where
        Self: Sized,
    {
        unsafe {
            let ct_key = sys::nftnl_expr_get_u32(expr, sys::NFTNL_EXPR_CT_KEY as u16);
            let ct_sreg_is_set = sys::nftnl_expr_is_set(expr, sys::NFTNL_EXPR_CT_SREG as u16);

            match ct_key as i32 {
                libc::NFT_CT_STATE => Ok(Conntrack::State),
                libc::NFT_CT_MARK => Ok(Conntrack::Mark {
                    set: ct_sreg_is_set,
                }),
                _ => Err(DeserializationError::InvalidValue),
            }
        }
    }

    fn to_expr(&self, _rule: &Rule) -> *mut sys::nftnl_expr {
        unsafe {
            let expr = try_alloc!(sys::nftnl_expr_alloc(Self::get_raw_name()));

            if let Conntrack::Mark { set: true } = self {
                sys::nftnl_expr_set_u32(
                    expr,
                    sys::NFTNL_EXPR_CT_SREG as u16,
                    libc::NFT_REG_1 as u32,
                );
            } else {
                sys::nftnl_expr_set_u32(
                    expr,
                    sys::NFTNL_EXPR_CT_DREG as u16,
                    libc::NFT_REG_1 as u32,
                );
            }
            sys::nftnl_expr_set_u32(expr, sys::NFTNL_EXPR_CT_KEY as u16, self.raw_key());

            expr
        }
    }
}

#[macro_export]
macro_rules! nft_expr_ct {
    (state) => {
        $crate::expr::Conntrack::State
    };
    (mark set) => {
        $crate::expr::Conntrack::Mark { set: true }
    };
    (mark) => {
        $crate::expr::Conntrack::Mark { set: false }
    };
}